The present invention relates to improvements in surgical tools and methods for their use by surgeons in performing anterior cervical discectomy and vertebral fusion, and in particular is related to a cooperative relationship between a retractor and a distractor.
In recent years, deteriorated cervical discs have been surgically replaced with an artificial disc or a bone graft used to fuse together the vertebrae between which the deteriorated disc had been located. The space between the vertebrae is approached by retraction of the muscles and structures in the anterior neck, using a retractor having blades conventionally held apart by a spreading mechanism which may include a crank or scissors mechanism to spread the retractor blades apart from each other. The currently used technique consists of dissecting the medial aspect of each longus coli muscle, the muscles that are attached to and which run parallel to the spine on either side of the midline. Retractor blades are inserted into and engage those muscles, and the muscles are pulled apart from each other laterally to provide access to the vertebrae and push against the trachea and other midline structures within the incision made by the surgeon, giving the surgeon a view of the anterior aspect of the cervical spine and the deteriorated disc.
This procedure, however, does not provide consistent retraction, and surgeons have had to adjust the retractor blades repeatedly during the procedure, since the retractor is not stabilized firmly and tends to loosen or shift its position. Conventional retractors tend to slip and to be torqued around from their intended positions and can tear paraspinous muscles or impinge harmfully on neck structures. When retractors slip or are moved out of their intended locations, the surgeon's view of the spine is impaired or occluded.
With soft tissue retracted sufficiently to provide access to the vertebrae, fixation pins are screwed into holes drilled into the vertebral bodies. A distractor is then attached to the fixation pins and is used to adjust the spacing between the vertebrae. The pins inserted into the vertebrae provide solid points of fixation utilized by the distractor.
Some previously available distractors, however, have tended to obstruct a surgeon's view of the disc space between the vertebrae into which the fixation pins are fastened.
Mayer et al. U.S. Pat. No. 5,728,046 discloses an apparatus in which retractor blades are carried on a frame defining an opening surrounding the location where surgery is to be performed. The apparatus also includes a pair of distractor bodies adjustably attachable to the frame and which can be attached to fixation screws fastened into the vertebrae between which a discectomy and fusion procedure is to be carried out. While the Mayer et al. device is adjustable in several aspects, its installation apparently requires complex manipulation of several parts at the same time.
What is needed, then, is an easily utilized system including a retractor for securely and reliably holding muscles and other structures of the anterior neck where they do not interfere with surgical procedures involving the cervical vertebrae, and a distractor for holding vertebrae in appropriate positions while affording a surgeon a clear view of a disc being replaced by a bone graft.